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Numerical Ability
Number System
how many 3 digits number are divisible by 7?
Read Solution (Total 6)
-
- 128
1st 3 digit number divisible by 7 = 105
last 3 digit number divisible by 7 = 994
105,(105+7),(105+2*7),....994
This is an AP with
1st term, a1 = 105
difference, d = 7
n th term, an = 994
a1+(n-1)d = an
105 + (n-1)*7 = 994
n-1 = 127
n = 128
- 10 years agoHelpfull: Yes(5) No(0)
- first number divisible by 7=105 and last 3 digit no=994
no of such numbers=(last -first)/(common difference)+1
=994-105/7+1
=128 - 10 years agoHelpfull: Yes(1) No(0)
- max num=999
min num=100
total 3 digit numbers (999-100)+1=900
900/7=128 its the short cut no consider the remender
- 10 years agoHelpfull: Yes(1) No(0)
- First 3digit no that divisible by 7 is 105 that is 15*7
and last 3digit no is 994 that 142*7 so
142-14=128total no divisible by 7 - 10 years agoHelpfull: Yes(0) No(0)
- 15*7=105 is the first 3digit
142*7=994 is the last 3 digit no
so 142-14=128no of 3digit no is divisible by 7 - 10 years agoHelpfull: Yes(0) No(0)
--> Total 3 digit numbers are 1000-100( i.e 1...99 and 1000) =900
--> 3 digit numbers that divisible by 7 are 900/7 =128
- 10 years agoHelpfull: Yes(0) No(0)
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